Semiempirical analytic formulas for large‐scale electric magnetospheric fields are developed that are valid within the inner magnetosphere as well as within the ionosphere. These electric fields drive ionospheric electric currents. Moreover, field‐aligned electric currents must exist in order to maintain the magnetospheric electric field configuration. The model calculations are compared and are shown to be consistent with the shape of the plasmapause, the equivalent electric current systems of DP 1 and DP 2, the available electric field observations at ionospheric altitudes, and the observations of field‐aligned electric currents.

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The 2.29 GHz S band carrier signals of the two Helios spacecraft are used to probe the magnetic and density structures of the solar corona inside 0.05 AU. In this paper we analyze the observed fluctuations of the electron content and Faraday rotation. A simple statistical ray analysis is employed. We conclude that (1) the observed Faraday rotation fluctuations cannot be solely due to electron density fluctuations in the corona unless the coronal magnetic field is some 5 times stronger than suggested by current estimates, and (2) the observed Faraday rotation fluctuations are consistent with the hypothesis that the sun radiates Alfvén waves with sufficient energies to heat and accelerate high‐speed solar wind streams.

The observed magnetospheric convection field at ionospheric heights is simulated by a simple analytic quasi‐static electric potential field. In particular, the transition region within the auroral zone where the meridional electric field component reverses is brought into close agreement with Heppner's (1977) observations. The location of zero meridional electric field strength in the model is compared with the observed Harang discontinuity (Maynard, 1974), where the zonal plasma flow reverses. The field‐aligned electric currents associated with the model electric field occur within two regions. In region 1, within the auroral zone, maximum outflow out of the ionosphere occurs at 1600 LT. In region 2, equatorward of the auroral zone, maximum outflow is near 0700 LT, consistent with measurements of Iijima and Potemra (1976).

Coronal Faraday rotation of the linearly polarized carrier signals of the HELIOS spacecraft was recorded during the regularly occurring solar occultations over almost a complete solar cycle from 1975 to 1984. These measurements are used to determine the average strength and radial variation of the coronal magnetic field at solar minimum at solar distances from 3-10 solar radii, i.e., the range over which the complex fields at the coronal base are transformed into the interplanetary spiral. The mean coronal magnetic field in 1975-1976 was found to decrease with radial distance according to r-=, where ~ = 2.7 + 0.2. The mean field magnitude was 1.0 + 0.5 x 10-s tesla at a nominal solar distance of 5 solar radii. Possibly higher magnetic field strengths were indicated at solar maximum, but a lack of data prevented a statistical determination of the mean coronal field during this epoch.